QUESTION: Can I use a trademarked word that’s registered in the UK, but not in the USA? Does that trademark apply to the US at all.
I want to revive a dead community website, I own the domain but upon further research I noticed the word mythros is trademarked in the United Kingdom. However, it’s not trademarked where I live in the USA.

ANSWER: One can have trademark rights without registration. Therefore, a company in the UK may have registered their trademark in the UK but may also have unregistered trademark rights in the US. These unregistered rights may have “priority” over your rights.